1. Unit 12: Tillage & Farming Systems Chapter 12

2. Objectives Historical trends in tillage Investigate reasons for tillage Different types of tillage Advantages/impacts of alternative tillage management Role of organic farming Uses & issues of transgenic crops

3. Purposes for Tillage Evolution of tillage:  Minimum tillage in primitive times – all hand work  As equipment became available – tillage increased to maximum tillage – now considered excessive & wasteful  Now going back to moderate – minimum tillage – fuel savings, healthier for soil, reduced labor costs, additional technologies for control of various yield reducers, better understanding of soils

4. Purposes for Tillage Seedbed Preparation  Most needed when planting small, high-cost seed (lettuce, clover) Less critical for vigorous, larger seeds (corn, wheat, soybeans)  Should be prepared according to preference of the crop being seeded Alfalfa – fine, firm soil, shallow seeding depth Wheat – dry, aerated soil, good infiltration & aeration

5. Purposes for Tillage  Tillage incorporates crop residue Difficult to plant through much residue  Seed may be left in residue, not in soil  Seed likely to die  Poor, erratic stand Weed Control  Weeds compete for soil water, nutrients, light  Tillage essential to deter weeds Especially before herbicides

6. Purposes for Tillage  Today – herbicides more effective at controlling weeds than tillage Also:  Eliminate field passes  Preserve soil moisture  Reduce damage to crop roots  Less developed countries = more hand tillage/cultivation  Farmers prefer aesthetically pleasing fields

7. Purposes for Tillage Loosening the Soil  Excessive tillage can cause extensive compaction Plow or Tillage Pan – zone of compaction just below tillage zone Greatly decreased infiltration rates, aeration, root penetration  Need corrective tillage to remedy, or grasslands

8. Purposes for Tillage Shaping the Soil  Flood & Furrow irrigation  Tillage forms ridges & furrows, and smoothes soil surface  Allows water to move equally through field for irrigation

9. Purposes for Tillage Incorporation of Lime & Fertilizer  Increases effectiveness and volatility of materials Control of Insects & Disease  Hessian fly – plow infested wheat stubble  Corn Borer – burying infests stalks  Grasshoppers, etc.

10. Purposes for Tillage Improving Water Relations  Break soil crusts, loosens soil, increases infiltration  Storage of even a little more water can be difference in profitable/unprofitable yields  Using subsoiler that leaves soil surface w/ little disturbance may increase water storage 3” through winter

11. Purposes for Tillage Aerating & Warming  Compacted, crusted soils have poor air exchange  Limits root growth, plant productivity  Poor microbe efficiency  Can speed temp warming, if desired (early spring planting)  Dries soil if excessively wet What is the risk of working wet soils?

12. Purposes for Tillage Reasons to Reduce Tillage or Eliminate Tillage  Must keep food production economical for producers & consumers  Reasons to reduce tillage: Eliminate/reduce erosion  Critical to keep topsoil in place for ag’s future  Gov’t pressure/regulation will force more conservation techniques

13. Purposes for Tillage Save time/fuel  Conventional tillage uses ~7.7 gal/ac of fuel  No-till consumes ~4.1 gal/ac fuel  So: 3.6 gal/ac fuel savings * $2.75 diesel = ~$10/ac * 1,000 ac farm = $10,000/yr  Might this be difference in profit/loss?  Potential benefits of reduced tillage: Improved air/water quality Decreased erosion Time Improved water storage in topsoil

14. Purposes for Tillage Double cropping more profitable Fuel Decreased compaction Soil tilth, organic matter improvements Increased wildlife habitat

15. Tillage Terminology Primary tillage – first & deepest tillage operation  Loosens soil  Moldboard plow, disc, chisel plow Secondary tillage – follow primary tillage  Disks, cultivator, harrow  Kill weeds, incorporate chemical/fertilizer  Prepare seedbed

16. Tillage Terminology Chisel – narrow shank pulled through soil to rip Chisel plow – rips soil 6 – 12” depth Conservation tillage – any tillage system that leaves >30% of surface covered by residue for erosion control

17. Tillage Terminology Conventional tillage – traditional moldboard plow, disc, harrow, seeding  Any tillage leaving <15% of surface covered by residue Coulter – disk w/ straight/fluted edge for slicing open soil Cultivator – small sweeps pulled between crop rows to kill weeds

18. Tillage Terminology Disk – combination gangs of concave disks to till soil Harrow – vertical tines to break clods Mulch till – surface tilled, residue remains No-till – no tillage, except for seeding & maybe fertilizer injection

19. Tillage Terminology Reduced tillage – combination of tillage operations  >15% <30% residue cover Ridge till – ridges formed by sweeps, etc. Shovels – narrow-winged sweeps Strip till – small strips where seeds planted tilled only

20. Reducing or Eliminating Tillage Tillage started to improve on nature’s methods of crop growth  Ability to grow more crop/land area  Option to grow a single crop in a field Physical Properties of Soil  Any traffic increases compaction  Tillage loosens soil to depth of tillage, but increases compaction on subsoil

21. Reducing or Eliminating Tillage  No-till – increases #/size of soil pores, soil protection & aggregation are improved w/ crop residue  Reduced & conservation till fields cooler & wetter in the spring Delays planting Reduces germination & early seedling growth

22. Reducing or Eliminating Tillage  Earthworms Improves population Greater positive effect on soil matrix  Water infiltration  Soil aeration  Deep tillage Still feasible to help open subsoil Rip at 12 – 16” depth Deep rooted crops can also help w/ compaction & reduce tillage

23. Reducing or Eliminating Tillage  Increases organic matter Organic matter % increases twice rate of increase in conventional till (in upper 2”) No difference in organic matter below 6” Other studies say no increase in organic matter  Increased yields Are we seeing that here?

24. Reducing or Eliminating Tillage Seedbed Preparation  Reduced till – works well for large-seeded crops Fine-seeded crops prefer more tillage, w/ pulverized, uniform seedbed  May see decreased seedling emergence, reduced stand density Especially if you don’t have a planter able to get through residue May use 10-15% more seed to compensate

25. Reducing or Eliminating Tillage Pest Control  Minimal tillage increases burden of weed control on herbicides  Will increased herbicide usage delete fuel/labor savings?  Maximize crop rotation effects  No-till may decrease weed stands long term Don’t work weed seeds into soil during tillage Reduced ability for weed seed to germinate  They need the same seed/soil contact as crops

26. Reducing or Eliminating Tillage  Increased dependence on insecticides as well More favorable environment to harbor them Bigger problem w/ soil insects, less opportunity to disturb their life cycle  What other risks are there if we depend more on chemicals for control of weeds/insects?

27. Reducing or Eliminating Tillage Fertilizer & Lime Applications  Reduced tillage limits ability to incorporate P, K, lime into the soil  Can result in a concentrated zone of nutrients in top 3” of soil May be acidified by N May cause shallow rooting

28. Reducing or Eliminating Tillage Organic Toxins  Allelopathy – toxins emitted by one plant affected growth of another Wheat on wheat Corn on corn ?  Leaving residue on the soil surface can increase the risk of toxins  Most injurious in early growth stages

29. Reducing or Eliminating Tillage Special Situations  Some crops won’t respond well to reduced tillage Have specific needs for tuber growth  Potatoes  Sugar beets Can be more susceptible to disease  Strawberries/cucumbers & fungal diseases  Excess residue problematic for surface irrigation Water not able to flow freely over soil surface Furrows need to be clean for efficient flow & help reduce erosion of ridges

30. Reducing or Eliminating Tillage Erosion Control  Greatly decreased wind erosion w/ reduced tillage  Advances in chemical technology allows for easier use of cover crops & burndown  Slows ability of water to wash soil from surface as easily

31. Farming Systems & Environmental Quality Reduced tillage increases dependence on chemical control of pests Typically increases pesticide use 15-40% Erosion of N, P and pesticides increased w/ reduced tillage Due to zone of accumulation nearer soil surface than conventional tillage Tillage itself is erosive

32. Farming Systems & Environmental Quality Carbon Sequestering – putting C back into the soil Driven by global warming theory  Elevated levels of CO 2 Soil used to/can be source of atmospheric C  w/ reduced tillage, becomes a recipient of atmospheric C

33. Farming Systems & Environmental Quality Water Quality  Studies indicating reduced tillage reduces water pollution risks  Even though more polluters concentrated at soil surface  So, what else is driving this trend?

34. Transgenic Crops GMO’s have drastically modified farming practices & options Genetically Modified Crops  Contains genes from another organism inserted artificially into a newly engineered crop RR soybeans  Weed control easier, more effective w/out damaging beans

35. Transgenic Crops  Bt Cotton Cotton resistant to the very damaging bollworm Insecticides often kill both damaging & beneficial insects  Bt Corn Bacillus thuringensis – protein that is toxic to the corn borer Pollen from Bt corn found to be lethal to monarch butterflies  Should it remain approved for use? Why?

36. Transgenic Crops Risks Associated w/ GMO’s  Potential for herbicide resistant plant or pollen to develop  Difficulty controlling escape of GMO pollen  Consumer concern over GMO grain entering human food system  Much debate over safety – no known health risks to humans or animals

37. Transgenic Crops Present Status & Trends  Most countries approve planting of GMO crops  Very little used in Japan, China, Europe  Government concerns Backlash from religious & environmental groups  Company risks Fear gov’t’s inability to enforce contracts Loss of their technology to competition

38. Sustainable Agriculture & Organic Farming Sustainable Agriculture – minimal use of resources (water, chemicals, energy) w/ little/no damage to environment  Balance of energy used vs. energy produced  Crop selection: choose proper crops for situation  Crop production: proper agronomic management w/ planting, cultivating, pest management, harvest. Maximize crop rotation benefits

39. Sustainable Agriculture & Organic Farming  Soil fertility: use legumes & manure wisely, use of commercial fertilizers sparingly, and manage their effectiveness  Soil conservation: minimal tillage for acceptable field conditions Use windbreaks, buffer strips, strip cropping when necessary Minimize soil compaction Maximize crop residue use

40. Sustainable Agriculture & Organic Farming Objectives of Organic Farming  Avoid inputs of synthetic substances  Produce healthy foods untainted by unnatural substances  Strategies: Use of manure & legumes for plant nutrients Tillage, crop rotation, manual labor for weed control Natural suppressants, repellants, & predators for insect & disease control

41. Sustainable Agriculture & Organic Farming Mixed Reviews for Organic Farming  Clearly less environmental problems Although may increase N loss to groundwater  Some decrease in energy use  Food quality superiority unfounded  20-45% reduction in yields (European study) Increased demand for land, w/ decreased output/ac

42. Sustainable Agriculture & Organic Farming Organic Food Marketing  Sales increasing sharply (especially in wealthy countries)  Fastest growing sector of world agriculture  Large export market for countries w/ highest % organic farming (Asia, Australia, Latin America) Ironic because of amount of fuel needed for transportation

43. Sustainable Agriculture & Organic Farming  Gaining Certified Organic Status Land have no prohibited substances applied for 3 yrs before harvesting an organic crop Use of genetic engineering, ionizing radiation, sewage sludge prohibited Fertility & nutrients managed through tillage, cultivation, crop rotation, cover cropping, supplemented w/ manure (limited synthetic materials)

44. Sustainable Agriculture & Organic Farming Prefer use of organically grown seed Pests, weeds, diseases must be controlled through management May only use approved synthetic substances  No zero tolerance standards – slight contamination (GMO’s) is allowed  Restrictions also encompass food processors  Livestock based organic production restrictions differ from crop production

45. Sustainable Agriculture & Organic Farming  Four levels of organic labeling 100% organic – seal on package 95-100% organic – seal on package 70-95% organic – can claim organic, but no seal <70% organic – can list organic ingredients, no organic claim or labeling

46. Assignment